An IC card is composed of a plane coil, in which a conductor line is wound a plurality of times, and a semiconductor element. The plane coil and other parts are enclosed and sealed by an adhesive layer made of polyurethane which is formed inside a resin film made of PVC, which forms a front surface and a back surface of the IC card, and letters are printed on a surface of the resin film.
When the thus formed IC card passes through a magnetic field formed by a card processor, electric power is generated by electromagnetic induction caused in the plane coil of the IC card. Therefore, the semiconductor element is started by the generated electric power, so that communication can be performed between the semiconductor element of the IC card and the card processor via the plane coil which functions as an antenna.
Concerning the conventional plane coil incorporated into the IC card, there is provided an insulated plane coil which is formed in such a manner that an insulation covered electric wire is wound, and also there is provided a plane coil which is formed in such a manner that a conductor line is formed when metallic foil formed on a resin film is etched.
In this connection, in order to promote the spread of IC cards, it is necessary to reduce the cost of IC cards and also it is necessary to mass-produce them. However, in the case of the above IC card in which the conventional plane coil is used, it is difficult to reduce the cost of the plane coil. Also, it is difficult to sufficiently mass-produce IC cards.
Therefore, Japanese Unexamined Patent Publication No. 6-310324 discloses an IC card into which a plane coil, which is formed by punching, is incorporated.
As proposed in the above patent publication, when the plane coil is formed by punching, the cost of the IC card can be reduced and the IC card can be mass-produced as compared with the IC card into which the conventional plane coil is incorporated.
FIG. 50 is a view showing a conventional plane coil 100 formed by punching. In this plane coil 100, terminals 102 and 104 are respectively formed inside and outside the coil.
Due to the above structure, a wire 114, which is one of the wires 112, 114 for connecting the terminals 102, 104 of the plane coil 100 with the electrode terminals 108, 110 of the semiconductor element 106, crosses a conductor wire 101 which forms the plane coil 100. Accordingly, when insulating covered wires are used for the wires 112, 114, the cost is raised, and a reduction in the cost of the IC card is difficult.
On the other hand, when a non-insulating wire is used for the wire 112 which does not cross the plane coil 100 and when an insulating covered wire is used for the wire 114 which crosses the plane coil 100, it becomes necessary to use two types of wires, and the manufacturing process of IC cards becomes complicated. Therefore, it is difficult to reduce the cost of IC cards and mass-produce them.
Since the thickness of the IC card is not more than 1 mm, it is necessary to form a very thin IC card. Further, plane coils formed by punching must be easy to handle when they are transported, and semiconductor elements must be appropriately incorporated into the plane coils.